1. Field of the Invention
The present invention relates to an ink jet recording apparatus. More particularly, the invention relates to an ink jet recording apparatus capable of detecting the presence and absence of ink with good precision.
2. Related Background Art
There have been proposed various recording apparatuses that record on a paper sheet, a resin sheet, or other recording media. Of those apparatuses that have been proposed conventionally, an ink jet recording apparatus is to discharge ink from its recording head onto a recording medium directly. It is possible to operate the ink jet recording apparatus at low running costs with a lesser amount of noises. Therefore, together with other advantages, the apparatus is now widely used.
Also, in general, an ink jet recording apparatus is provided with recovery means for maintaining and recovering the ink discharging function of an ink jet recording head mounted on it. This recovery means comprises, among others, a cap member to cover the ink discharge ports of the ink jet recording head, and receive ink discharged from the ink discharge ports; a blade formed by an elastic material or the like to clean the head surface by sliding on the head surface having the ink discharge ports; a driving source to enable the cap member to be in contact with or move away from the head, and the blade to move slidably; and a pumping mechanism to cause the waste ink, which has been discharged to the interior of the cap member, to be exhausted outside the cap member.
A serial type ink jet recording apparatus is arranged to mount an ink jet recording head on a carriage that reciprocates for recording on a recording medium. This apparatus is provided with a recording area within the traveling range of the carriage, where ink jet recording is possible on a recording medium (in general, a platen is arranged on this recording area), and also, with a non-recordable area on one end portion adjacent to such recording area, where the aforesaid recovery means is inclusively arranged.
Among those ink jet recording apparatuses, there are some for which detection means is provided to detect ink. For the structure of such detection means, a method is adopted, among some others, to provide a recording medium or a film sheet with a mark for use of detecting the presence and absence of ink, and then, to detect whether or not such mark is recorded by means of a photosensor or a method is adopted to discharge ink between the light emitting element and photodetecting element of a photointerrupter, and then, to detect the presence and absence of ink by the output that changes when ink crosses the optical axis of the photointerrupter.
However, with respect to the ink detection structures described above, there is a need for a structure in which a mark should be recorded directly on a recording medium or a film sheet for detecting the presence and absence of ink. This is the provision of a mark that is not fundamentally needed for the performance of any regular recording, although the detection can be effectuated in high precision by means of this method.
Also, for the method to detect the presence and absence of ink by means of output changes when ink crosses the optical axis of a photointerrupter, there is a need for the provision of a system to collect discharged ink as waste ink, simply because ink should be discharged to execute such detection. Therefore, the location where this detection is conveyed out is usually arranged in the vicinity of a suction pump, which is used for preventing the recording head from being clogged. In this way, it is made possible to share the waste ink disposition system for use of such detection and prevention. Nevertheless, the optical components constituting the photointerrupter are stained by ink splash from the blade provided for wiping off unwanted ink droplets adhering to the circumference of nozzles of the head after ink is sucked by the suction pump, as well as by ink splash from some other peripheral members of the blade. If the optical components are stained, there is a fear that detection is erroneously executed.